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, J. M. DAVIDSON. MANUFACTURE OF THREAD PROTEGTORS FOR PIPES AND BOLTS.

No. 560,610. Patented May 19, 1896.

ANDREW BJSRAKAM PHQTO-LITHQWASNINGTUN. D C

UNITED STATES ATENT OrFicE.

JOHN M. DAVIDSON, OF ALLEGHENY, PENNSYLVANIA, ASSIGNOR TO I. 'MCDOWVELL AND D. F. H. MCDOWVELL, OF SAME PLACE.

MANUFACTURE OF THREAD-PROTECTORS FOR PIPES AND BOLTS.

SPECIFICATION forming part of Letters Patent No. 560,610, dated May 19, 1896.

Application filed October 4, 1895. Serial No. 564,610 (No specimens.)

To cLZZ whom it may concern.-

Be it known that I, JOHN M. DAVIDSON, a citizen of the United States, residing at Allegheny, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in the Manufacture of Thread-Protectors for Pipes and Bolts; and I do hereby declare the following to be a full, clear, and exact description of the invention,

IO such as will enable others skilled in the art to which it appertains to make and use the same.

My present invention relates to the manufacture of thread-protectors for pipes and I 5 bolts, and has for its objectcertain improvements which will be fully disclosed in the following specification and claim.

Thread-protectors as heretofore constructed have been made of sheet metal with flanges 2o bent inwardly on the edges and of a bar of iron with parallel threads on one surface and the bar cut into suitable lengths to form rings of various diameters. The blanks with their threads formed in them are provided with a male and a female dovetail on opposite ends and are bent into an annulus and the dovetail members engaged. The threads on the protector being parallel to each other and the threads on the pipes or bolts being spiral, the threads of the former do not mesh with the threads of the latter, but at certain points they cross each other, which causes the threads to jam upon each other, and in the event of a pipe falling heavily or another 3 5 pipe falling upon it the threads of the pipe are bruised or battered by the threads of the presumed protector and injured for use. Furthermore,in order to make the parallel threads of the protector engage with the spiral threads 0 of the pipe the protector does not engage the pipe at that part where the ends of the blank have been joined to form the annulus, and as a consequence the dovetail members of the protector frequently become disengaged in handling pipe by a fall or other concussion. It is my purpose to obviate the difliculties attending the construction of this class of articles by providing a perfect ringprotector that is provided with spiral threads of the pitch of the threads on the pipe and that shall have the greatest thickness of metal on the edges of the protector subject to the greatest amount of rough usage in handling and transportation and provide the least surface practicable with screw-threads in order to reduce friction in applying and removing the protector to the minimum.

In the accompanying drawings, which form part of this specification, Figure 1 represents a plan view of ablank for a thread-protector cut from a bar of channel-iron for the purpose; Fig. 2, a transverse section of the same; Fig. 3, a plan view of the blank with the tongue bent to form a recess to receive and overlap the opposite end; Fig. a, a side elevation of the completed protector; Fig. 5, a transverse section of the same, and Fig. 6 an enlarged detail section through the lap of the ring.

Reference being had to the drawings and the letters thereon, A indicates a blank which is provided with reinforced edges a b and a rabbet 0 between them, which makes the bar from which the blank is cut channel-iron especially adapted for this purpose. On one end of the blank is a tongue cl, which'is formed of the metal between the reinforces a b and which is bent back to form a recess e to overlap the opposite end f of the blank when the blank is bent into the form So of a ring, and the endfis cut back at g to enable the reinforces to be brought together and form continuous and unbroken annular screw-threaded surfaces to engage the screwthreads of a pipe or bolt. The blank is bent into a ring B by suitable machinery and the tongue at secured to the opposite end of the blank by a rivet h, when the ring is placed in a suitable die andascrew-tap inserted in the ring and spiral screw-threads 2' i cut in the surfaces of the reinforces CL b. The reinforces may be of any desired width and vary with the width of the ring; but as a rule their width need not exceed the thickness thereof. The blanks having been bent into perfect cylinders and the ends permanently secured, the rings when completed retain their shape, and in consequence of the perfection of the cylinders and their being held in a die While the screw-threads are being cut the threads are perfect and engage the threads of a pipe throughout the entire surface of the reinforces.

The several steps in the operation of mak ing the protector, stated consecutively, are: The bar from which the blanks are made is rolled from a suitable heated billet in the usual Wa y of rolling channel-iron and the bar allowed to cool, when the cold bar-is cut into blanks of the configuration described. The cold blanks are then punched near each end to form rivet-holes. The blanks are then bent into rings by suitable rolls, and the rings, with the tongue overlapping the opposite end of the blank and the rivet-holes registering, are placed in a suitable die and a rivet put in the holes, when by a stroke or pressure brought to bear upon the overlapping ends the tongue is bent outward to form a seat for the opposite end of the blank and the rivet upset in the holes in the ring and the ends permanently secured together. The

ring is then screw-threaded internally upon the surfaces of the reinforces by a suitable tap Working from one side of the ring.

Having thus fully described my invention, what I claim is The method of making thread-protectors, which consists in heating a billet and rolling it into a bar having reinforces on its edges and a rabbet between the reinforces said reinforces being of greater thickness than. the metal between them, cooling the bar, severing the cold bar into blanks and forming a tongue on one end of the blank and a recess in the opposite end, punching rivet-holes in each end of the blank, then bending the cold blanks into an annulus With one end over lapping the other, securing the ends together permanently and finally screw-threadin g the inner surfaces of the reinforces.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN M. DAVIDSON. \Vitnesses:

D. O. REINOHL, D. WEIMER REINOHL. 

